A pressurized core cowl refers to a sealed core compartment of a core case of a turbofan gas turbine engine, to use a portion of a bypass air to cool engine components located within the core compartment. In a pressurized core cowl the pressure differential (ΔP) available to bypass air an active tip clearance control (ATCC) apparatus is limited. In low ΔP situations, a scoop is often used in a bypass air duct to create a dynamic pressure head, in order to create the required pressure differential in the pressurized core cowl to drive the ATCC apparatus. However, the resulting driving pressure may be marginal and the scoop may impact bypass duct performance. A scoop-less system may be possible if the core compartment is vented with respect to atmospheric pressure, but this may degrade engine performance because the portion of bypass air introduced into the core compartment is no longer returned to the engine for thrust recovery.
Therefore, there is a need to provide an improved ATCC apparatus.